Elevator door operator with differential torque motor system

ABSTRACT

Elevator door operator using a differential torque motor system which is particularly advantageous in opening and closing the doors of passenger and freight elevators. The motor system provides a first torque in moving the door to the open position and a second, lower torque in moving the door to the closed position. The force moving the door to the closed position is so limited as to be within the range of present safety regulations which limit the force necessary to prevent closing of such elevator doors from rest to no more than 30 pounds. The differential motor control is obtained by utilizing series and shunt field windings which are selectively cumulatively compounded for opening and differentially compounded for closing.

United States Patent Inventor Henry J. Holuba Moline, Ill. Appl. No. 794,100 Filed Jan. 27, 1969 Patented Sept. 14, 1971 Assignee Montgomery Elevator Company ELEVATOR DOOR OPERATOR WITH DIFFERENTIAL TORQUE MOTOR SYSTEM Primary Examiner--Harvey C. Hornsby Attorney-Hofgren, Wegner, Allen, Stellman & McCord ABSTRACT: Elevator door operator using a differential torque motor system which is particularly advantageous in opening and closing the doors of passenger and freight elevators. The motor system provides a first torque in moving the door to the open position and a second, lower torque in moving the door to the closed position. The force moving the door to the closed position is so limited as to be within the range of present safety regulations which limit the force necessary to prevent closing of such elevator doors from rest to no more than 30 pounds. The differential motor control is obtained by utilizing series and shunt field windings which are selectively cumulatively compounded for opening and differentially compounded for closing.

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ELEVATOR DOOR OPERATOR WITH DIFFERENTIAL TORQUE MOTOR SYSTEM BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to motor systems of general application which are especially adapted to elevator door'operation.

2. Description of the Prior Art In conventional elevator door operating systems, direct current motors are utilized for opening and closing the elevator doors. The door controls are arranged to provide substantially instantaneous reversal of the operating motor asa result of engagement by a person or object with safety devices such as a safety edge automatic reopening device or an electric eye automatic reopening device. However, most such systems have a time override so that a passenger cannot immobilize the elevator car for an indefinite time by standing in the doorway; and when the time override functions there must be a limit on the stalled torque. Further, in the event of failure of the safety devices the closing torque, and especially the stalled torque, must be relatively low.

In the conventional elevator door controls, the reversing of the direct current motor is effected by maintaining the shunt field polarity while reversing the armature polarity by suitable automatic switches.

To provide safety in the use of such elevator door controls, a standard has been set limiting the stalled torque of the motor in the closing direction to permit a force of no more than 30 pounds to prevent closing of the door from rest. It is desirable to provide a greater torque for quickly moving the door to the open position. To provide such differential torques, it has been customary in the art to utilize friction clutches, currentsensitive relays, and the like. The known devices for providing such differential torques have the serious disadvantages of relative high cost, complexity, variability of operation, relatively high maintenance, and the like.

SUMMARY OF THE INVENTION The present invention comprehends an improved elevator door operator utilizing a. differential torque motor system which eliminates the need for the above-discussed differential torque devices while yet providing acceptable door-opening tion, and in a second arrangement to develop a lower torque to move the door toward the closed position.

BRIEF DESCRIPTION OF THE DRAWINGS Other features and advantages of the invention will be apparent from the following description taken in connection.

I system.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the exemplary embodiment of the invention as disclosed in the drawing, an elevator apparatus generally designated 10 is shown to include a conventional elevator car 1I defining a doorway opening 12 and provided with a door 13 for'selectively closing the doorway opening. The elevator 11 is illustrated in FIG. 1 as at a landing generally designated 14. A hoistway, or hatchway, door 15 is provided at landing 14 in movable association with wall 16 to provide controlledaccess at the landing through the car doorway 12. The elevator door 13 and hatchway door 15 are interengaged for concurrent opening of the two doors when the car door 13 is moved to an open position with the car 11 at landing I4. 1

The operation of car door 13 is effected through a mechanism generally designated 17 of conventional construction for delivering door opening and door closing forces to door 13 from a drive motor. 18, herein a direct current motor. The operation of motor 18 for moving door 13 selectively to the open and closed positions is controlled by a conventional door operator control generally designated 19 (FIG. 2).

Control 19 is responsive to a conventional safety edge device 20 provided on door 13. Safety edge" device 20-functions in the conventional manner through control 19 to reverse the motor 18 to substantially instantaneously drive the door toward the open position when device 20 is engaged by a person or object while the door 13 is moving toward the closed position. Such safety edge controls are well known in the art and require no further description herein.

As indicated briefly above, the invention comprehends the provision of means for controlling motor 18 to provide an imspeed in combination with a lower closing torque and especially a stalled torque that meets the safety standards set for automatic elevator door operation.

More specifically, the invention comprehends utilizing series and shunt field windings of a'direct current motor selectively in cumulatively and differentially compounded arrangements to provide accurately controlled differential torques. The selective arrangement of the field windings provide a variation in the total magnetism to effect the desired control. More specifically, the selective arrangement provides an improved control of the stator magnetic flux.

The invention affords the further highly desirable feature of providing minimum torque in the closing direction when the motor is stalled with higher torque when the motor is moving the door toward the closed position. The ratio of the shunt field to series field ampere turns may be suitably selected to provide a selected differential in the door closing and door opening torques.

Further, the use of the series field winding in conjunction with the shunt field winding produces an increase in the motor torque over that provided by the shunt field winding alone, thereby providing high torques for use in controlling relatively heavy doors.

More specifically, the invention comprehends the provision of improved means for driving a mechanism such as an elevator door which includes a direct current electric motor having a shunt field, a series field and an armature rotatably driving the mechanism, and circuit means connecting the shunt field, series field and armature selectively in a first arrangement to develop a high torque to move the door toward the open posiproved differential torque operation. More specifically, the apparatus 10 includes a control circuit generally designated 21 (shown in FIG. 2) for reversely controlling the motor 18in conjunction with the door operator control 19. As shown, the control 21 may be operated from a suitable direct current supply through leads LI and L2. The motor 18 includes an armature 18a, a shunt field 18b and a series field 18c. Control 21 is arranged to provide selectively cumulative compounding and differential compounding of the 'motor l8-as a function of the operation of door operator control 19. More specifically, control 19 controls the operation of pair of normally open door closing contacts C-1 and G2 and a pair of normally open door opening contacts 01 and 0-2. Further, control 19 provides for dynamic braking of the motor through control of normally closed contacts l-Cl and 4-01, and controls the speed of the motor through a pair of slowdown relay contacts SDRl and SDR2. Automatic speed control is obtained, when the elevator is operating without an attendant, by means of contacts D06 and l-Cl'.

More specifically, as shown in FIG. 2, the shunt field 18b is connected across the leads L1 and L2, contacts C-1 and 0-1 are connected in series between the leads L1 and L2, and contacts 0-2 and G2 are connected in series therebetween. Normally closed contacts SDR2 are connected from the armature 18a to between contacts 0-2 and C-2, and the series field is connected from the armature 18a to between the contacts C-1 and 0-I. Contacts l-CI and 4-01 are connected in a closed series loop with armature 18a and series field 180. A rheostat generally designated RES-E has its resistance portion 22 connected in series with normally open contacts SDRl from between contacts -2 and C-2 to between contacts C-1 and 0-1. The adjustable, contact 23 of rheostat RES-E is connected to between armature 18a and contacts SDR2. Contacts D06 and l-C1' are connected in series across contactsSDRl.

In operation, control.2l functions to selectively-reverse the series fieldl8c relative to the shunt field 18b to provide selectively cumulatively compounded and differentially com-.

pounded operation of motor 18. Thus, when the door operator control 19 is activated to effect a door-opening operation such as at landing 14, the control 19 causes normally open contacts 0-2 and 0-1 to close, thereby completing a circuit from power supply lead L1 through closed contacts 0-2, normally closed contacts SDR2, armature 18a, series field 18c, and closed contacts 0-1. As shunt field 18b is energized across the power supply, the motor 18 is caused to drive door 13 through mechanism 17 toward the open position with a preselected high torque, series field 180 being connected in a cumulatively compounded direction relative to the shunt field 18b at this time.

When door operator control 19 is activated to effect a closing of door 13, normally open contacts C-1 and C-2 are closed thereby to provide a circuit from power supply Ll through closed contacts C-l, series field 18c, armature 18a, slowdown relay contacts SDR2 and closed contacts C-2 to power supply lead L2. Shunt field 18b remains connected in the same direction across power supply leads L1 and L2 and, thus, series field 18c is now connected in an opposite sense relative to the shunt field 18b to provide a differentially compounded operation of the motor 18 whereby the torque developed by motor 18 is reduced as compared to the torque'developed in the door-opening operation.

In the full open and full closed positions of the door, the contacts C-l, C-2, 0-1, and 0-2 are open. During operation of the motor 18, control 19 causes normally closed contacts 1- Cl and 4-01 to open. At the time the door reaches either the fully open or the fully closed position, control 19 causes contacts l-Cl and 4-01 to reclose, thereby providing a dynamic braking of the motor 18 for positively stopping the motor and door in the preselected fully opened or fully closed position.

Speed control of motor 18 is obtained through control of the contacts SDRl and SDR2. Thus, control 19 may be operated to open normally closed contacts SDR2 and close normally open contacts SDRl to thereby place the rheostat RES-E in the circuit with the motor armature and series field. More specifically, upon opening of contacts SDR2 and closing of contacts SDR], a circuit is established in the door-closing operation from power supply lead 1.1 through closed contacts C-l, series field'18c, armature 18a, rheostate moving contact 23, a portion of resistor 22, and closed contacts'C-2 to power supply lead L2. The resistor 22 resistance in series with the armature efiectively reduces the current flow therethrough correspondingly reducing the torque output. In addition, the remaining portion of resistor 22 is connected through closed contacts SDRI in parallel with'the series connection of armature 18a and series field 18c thereby reducing the voltage thereacross and further reducing the torque developed by the motor at this time. Thus, the torque on the closing of the door 13 is reduced to a preselected value as controlled by the setting of the rheostat RES-E.

Where the control of the door is set for automatic operation, i.e., without an attendant, the switch D06 is maintained closed. The contacts l-Cl' are closed by control l9'concurrently with the closing of contacts 01 and C-2 during the door 18 when the motor 18 is stalled during an attempted closing of the door 13, ascompared to the torque developed thereby On the other hand, the cumulative compounded arrange-- ment of the series field relative to the shunt field when the control 21 is arranged for energizing the motor 18 to open the door 13 provides an increased torque over that provided'solely by the shunt field 18b and, thus, a more powerful positive opening of the door is effected. Thus, the apparatus 10 is adapted for use where a relatively heavy door must be opened quickly and positively. As will be obvious to those skilled in the art, the specific amount of compounding may be controlled by suitably selecting the desired ampere turns of the respective fields to provide the desired differential door closing and door opening torques.

The apparatus 10 is illustrated in conjunction with a gearless type door operator mechanism 17. As will be obvious to those skilled in the art, any other suitable mechanism for driving the door from the motor may be utilized.

A further advantage of the control 21 is the low cost thereof afforded by the provision of the conventional series field-armature series connection directly in the control so that the selective cumulative and differential compounding is automatically effected by the conventional door closing and door opening control circuit contacts. Thus, the control 21 provides the highly desirable features discussed above while yet the control is extremely simple and economical of construction.

The foregoing detailed description is givenfor clearness of understanding only and no unnecessary limitations should be understood therefrom, as modifications will be obvious to those skilled in the art.

Iclaim:

1. in an elevator system having a car provided with a doorway, a door movable across said doorway, and mechanism arranged to be selectively driven to move said door selectively to open and closed positions, improved means for driving said mechanism comprising: a direct current electric motor having a shunt field, a series field, and an armature rotatably driving said mechanism; and circuit means for connecting said shunt field, series field, and armature selectively in a first arrangement to develop a high torque to move said door from said closed position to said open position, or in a second arrangement to develop a torque to move said door from said open position to said closed position, said circuit means in said second arrangement defining means for causing the torque to vary as an inverse function of the magnitude of retarding forces acting on said door while said door is moving to said closed position such that closing movement of the door is prevented whenever the magnitude of the retarding force is greater than a preselected value.

2. The elevator door driving means of claim 1 wherein said shunt and series field are cumulatively compounded in said first arrangement.

3. The elevator door driving means of claim 1 wherein said shunt and series field are differentially connected in said second arrangement.

4. The elevator door driving means of claim 1 further including resistance means and manually adjustable means for selectively connecting said resistance means in said circuit means for reducing the torque developed by said motor in each of said arrangements. r

5. The elevator door driving means of claim 1 further including means for selectively short-circuiting the series connection of the series field and armature to effect a dynamic braking operation. 7 l 1 6. The elevator system mechanism of claim 1 wherein said circuit means connects said shunt field, series field, and armature to develop a stalled torque tending to move said door to torque for moving said door toward said closed position.

8. The elevator system mechanism of claim 1 wherein said circuit means connects said shunt field, series field, and armature selectively in a first arrangement wherein the shunt andseries fields are cumulatively compounded to develop a torque to move said door toward said open position, or in a second arrangement wherein the shunt and series fields are differentially connected to develop a torque to move said door toward said closed position. 

1. In an elevator system having a car provided with a doorway, a door movable across said doorway, and mechanism arranged to be selectively driven to move said door selectively to open and closed positions, improved means for driving said mechanism comprising: a direct cUrrent electric motor having a shunt field, a series field, and an armature rotatably driving said mechanism; and circuit means for connecting said shunt field, series field, and armature selectively in a first arrangement to develop a high torque to move said door from said closed position to said open position, or in a second arrangement to develop a torque to move said door from said open position to said closed position, said circuit means in said second arrangement defining means for causing the torque to vary as an inverse function of the magnitude of retarding forces acting on said door while said door is moving to said closed position such that closing movement of the door is prevented whenever the magnitude of the retarding force is greater than a preselected value.
 2. The elevator door driving means of claim 1 wherein said shunt and series field are cumulatively compounded in said first arrangement.
 3. The elevator door driving means of claim 1 wherein said shunt and series field are differentially connected in said second arrangement.
 4. The elevator door driving means of claim 1 further including resistance means and manually adjustable means for selectively connecting said resistance means in said circuit means for reducing the torque developed by said motor in each of said arrangements.
 5. The elevator door driving means of claim 1 further including means for selectively short-circuiting the series connection of the series field and armature to effect a dynamic braking operation.
 6. The elevator system mechanism of claim 1 wherein said circuit means connects said shunt field, series field, and armature to develop a stalled torque tending to move said door to the closed position which is less than the torque developed by the motor when moving the door to said open position.
 7. The elevator door driving means of claim 6 wherein said circuit means includes means connecting the shunt field, series field, and armature to develop a high torque for moving said door toward said open position and develop a lower torque for moving said door toward said closed position.
 8. The elevator system mechanism of claim 1 wherein said circuit means connects said shunt field, series field, and armature selectively in a first arrangement wherein the shunt and series fields are cumulatively compounded to develop a torque to move said door toward said open position, or in a second arrangement wherein the shunt and series fields are differentially connected to develop a torque to move said door toward said closed position. 